When growing root crops, for example potatoes, carrots and the like, it is difficult to monitor various growth characteristics of the crop because the root or associated root-like structures are buried in the ground. Sampling of the progress of the growth of the root or root-like structure thus requires destructive sampling by unearthing the root or root-like structures. Due to this inconvenience, less sampling is done, resulting in such conditions as disease or underdevelopment due to lack of water or fertilizer going undetected. At the same time, to optimize growing conditions it is desirable to monitor other growth characteristics in addition to the size and mass of the roots or roots-like structures, including soil moisture content and the like.
Electrical Impedance Tomography (EIT) is a known technology developed to image the electrical conductivity distribution of a conductive medium. The technology is of interest because of its low cost and also because the measurement of electrical conductivity brings direct information about the composition of the conductive medium. Until recently EIT has been researched primarily for medical application. The technology has also been applied in the soil for the purpose of detecting landmines and unexploded ordinances. The detection process essentially measures three-dimensional perturbations in the local environmental electrical conductivity.